Retard feed apparatus with noise suppression device

Abstract: A retard feeder system having a noise suppression device which feeds sheets from a stack of sheets to a sheet transport path. The device includes a sheet feeding friction device (104) for engaging and moving sheets in a direction toward the path, a retard pad (202) positioned adjacent said sheet feeding device to form a retard nip to permit selective feeding of individual sheets through the retard nip to the path, and a raised portion (206) in the path for corrugating the sheet as portions of the sheet are engaged in the retard nip. The corrugation of the sheet helps to minimize the sheet flutter and vibration while it is within the retard nip by increasing the beam strength of the sheet and thereby decreases the audible noise created by the vibrating sheet.

Description: This invention relates to a sheet feeding apparatus having a noise suppression device therein. Various apparatus and techniques have been developed and used to transport the sheets from the sheet trays in an effective and efficient manner. These devices include so-called retard feeders which can include generally a transport actuator, such as a friction roller or belt for engaging a surface of a particular sheet to move the sheet along a path and a pad or other retard surface proximate the transport actuator for engaging the surface of and retarding the transport of other sheets tending to move with the particular sheet. In these devices, there is, however, a problem associated with such transports in that often the transport of the sheets by the sheet actuator and the retard surface is accompanied by an audible noise. Thus, there exists a need to provide a retard feeding apparatus, which for increased convenience, utility and versatility of such retard feeding apparatus, exhibits both a reduced noise volume in the transport of sheets, as well as, fewer incidents of noise associated with the the transport of sheets thereby. U.S.-A- 4,901,117 to Derrick, incorporated by reference into this application, discloses a sheet feeder having plural copy sheet trays for retaining sheets to be fed therefrom to a common path for transport to a transfer station of an electrophotographic printing machine. The sheet trays are arranged in a substantially horizontal plane with respect to each other. U.S.-A- 4,660,963 to Stemmle, incorporated by reference into this application, discloses a sheet feeder having plural copy sheet trays for retaining sheets to be fed therefrom to a common path for transport to a transfer station of an electrophotographic printing machine. As further disclosed within this reference, both trays from which copy sheets are fed, disposed in a substantially horizontal co-planar arrangement in a unitary drawer which can be slid away from the printing machine to load sheets, as desired. The device also includes a mechanical loading apparatus for one of the trays so that sheet previously imaged are returned for later duplex imaging. U.S.-A- 5,004,218 to Sardano discloses a retard type bottom sheet separator, in which the bottom of a stack of original document sheets is driven downstream to a separation nip with a retard pad by the planer upper flight of a driven frictional separator bottom feed belt. A shoe unit with a large planar overlying the belt assists feeding by applying a normal force on the sheets. US-A-5,083,766 discloses an electrophotographic printing machine comprising sheet feeding means and a noise damping member within the sheet guide passage. JP 61162437 discloses a paper sheet separating and guide device to prevent slipping sound from occurring between a transfer roll and a stationary roll and between a paper and stationary roll. According to the present invention there is provided an apparatus, electrophotographic printing machine and method in accordance with the appended claims. In accordance with one aspect of the present invention, there is provided an apparatus for feeding individual sheets while reducing the noise associated therewith. The apparatus comprises means for advancing and separating individual sheets in a first direction and means, adjacent the advancing and separating means, for dampening sheet flutter and reducing the noise associated therewith. Pursuant to another aspect of the present invention, there is provided an electrophotographic printing machine of the type in which individual sheets are fed from a stack by a feeder having a device to reduce the noise associated therewith. The improvement comprises means for advancing and separating individual sheets in a first direction and means, adjacent the advancing and separating means, for dampening sheet flutter and reducing the noise associated therewith. The feeding apparatus is feeding sheets from a stack of sheets along a paper path. The feeding apparatus comprises a friction pad positioned along the path and a roller positioned proximate the pad so that a sheet feeding nip is formed between the pad and the roller, the roller adapted to urge individual sheets from the stack through the nip. A means for dampening sheet vibration positioned to contact a sheet exiting the nip while a portion of the sheet is in the nip is also provided. In accordance with yet another aspect of the present invention, there is provided a method for reducing noise generated by feeding sheets by a retard pad feeding apparatus. The method includes urging at least one sheet in a sheet feeding direction to a retard nip and transporting a sheet through the nip in the sheet feeding direction. The step of damping the vibrations induced in the transported sheet while in the nip so that audible noise generated by the transporting step is inhibited is also provided. The present invention will be described further, by way of examples, with reference to the accompanying drawings, in which: Figure 1 is an enlarged elevational view of a sheet feeding system incorporating the features of the present invention therein; Figure 2 is an enlarged elevational view of a prior art retard feeder; Figures 3A and 3B are enlarged elevational views illustrating the operation of a first embodiment of the present invention; Figure 4 is an enlarged elevational view showing of a second embodiment of the present invention; and The invention will now be discussed in greater detail with respect to Figure 1 which represents a copy sheet feeding device or transport 3 constructed in accordance with an embodiment of the present invention. The transport in this embodiment is adapted for feeding sheets to image processing stations. In this embodiment, the sheets are fed to stations D and E of an illustrative electrophotographic printing machine (otherwise not shown). The station D is a transfer station having a belt 10 with a photoconductive surface 12 and corona generator device 32 positioned thereat. The exemplary fusing station E comprises a heated roll 34 engaged by a pressure roll 36 forming a sheet receiving nip. A motor (not shown) is suitably connected to actuate the rollers so that sheets in the nip are urged therethrough. The copy sheet transport 3 depicted in Figure 1 includes a sheet feeding means which includes a removable cartridge or cassette 59 in which sheets 60 may be positioned for feeding by a segmented roll 67 along a path 50 to registration rolls 70. The feeding means also includes a bypass feeding means which includes a driving roll 75 for transporting sheets under the segmented roll 67, in the position shown, to the path 50 and registration rolls 70. The copy sheet transport 3 also includes a first sheet bin or tray 40 and a second sheet tray 92, incorporating the noise suppression device of the invention herein, on a substantially horizontal plane, a third sheet tray 100 and a fourth sheet tray 102, each, are positioned in substantially vertical planes with respect to the plane of the trays 40 and 92, and both trays 100 and 102 are positioned in substantially the same horizontal plane, Preferably, the trays 40 and 92 are supported in a slidable drawer mechanism, as are the trays 100 and 102. Sheets positioned in each of the stacks may be selectively fed to the depicted stations D and E. Sheets from the stack disposed in tray 40 and 92 are fed by feed rolls 103 and 104, respectively. These feed rolls and the trays may be mounted in a suitable known manner, but it is preferred that they are mounted on a toggle carriage, substantially as described and disclosed in U.S. Patent No. 4,660,963, incorporated herein by reference, to enable selective feeding from the trays 40 and 92. Sheets actuated by the feed roll 103 from tray 40 are urged along a concave baffled surface 105 for transport upwardly from the stack of sheets to take away rolls 108. Sheets from the stack of sheets in tray 92 are also urged along a baffle surface 106 to the take away rolls 108 by the feed roll 104, as will be discussed in further detail below. Sheets from the stack of sheets in the tray 100 and sheets from the stack of sheets in tray 102 are actuated from their respective stacks in substantially the same manner by selectively actuable segmented feed rolls 110 and 112, respectively. The rollers 110 and 112, when feeding sheets from the respective stacks with which they are associated, are rotated into frictional engagement with the top sheet to urge the top sheet along one of concave surfaces 124 and 126 of double sided baffle 128 to the lower take away rolls 130. The lower take away rolls 130 urge sheets therein upwardly to the take away rolls 108 through an aperture 132 found between the baffle surface 105 and the baffle surface 106. Sheets engaged by the take away rolls 108 are in a common transport path 150 for transport to the process stations D and E. Specifically, sheets selectively fed from the trays 40, 92, 100, and 102 enter a common path 150 commencing just prior to take away rolls 108. These sheets are urged along the common path 150 by the take away rolls 108 to registration rolls 70 to promote registered transport of the sheets through the transfer station D and to urge the sheets through the station D and to the fusing station E. In the fuser station E the heating roll 34 and pressure roll 36 are actuated so that toner images on sheets passing therethrough are fixed to the sheets and the sheets are also urged to reversible rolls 160. The reversible rolls 160 initially are rotated to urge a sheet partly into output tray 38. The action of the rolls 160 may continue so as to deposit the sheet in the tray 38 or may be reversed to drive a sheet therein along a return path 162, which includes driving rolls 164 and a gate 167. The gate is selectable positionable to direct sheets along immediate or trayless duplexing path 42 for return to the common path 150 or into tray 40 for selective return to the common path. Sheets are fed from the stack in tray 92 by actuation of the roller 104 to a feeding position where the roller frictionally engages the surface of a sheet in the tray to urge it toward a retard pad 152 on the baffle surface 106 which forms a nip with the roller 104. A known retard pad feeding configuration is illustrated in Figure 2. As is well known, the urging of the sheet toward the retard nip also causes other sheets in the stack to move toward the nip. The retard pad 152 is formed of a material which exerts a frictional force on the sheets greater than the frictional force between the sheets so that the lower sheets tend to slip as the upper sheet to be fed moves through the nip by roller 154. Thus, feeding of single sheets as desired is enabled. Turning now to Figs. 3A and 3B, the operation of the retard feeder with the noise suppression device of the present invention will be discussed. The retard feeder 200 consists of a feed roll 104, a retard pad 202, and a flexible resilient strip 206 located downstream of the retard nip. As a sheet 250 is frictionally contacted by the feed roll 104 and fed from the top of the sheet stack 300, the sheet is caused to enter the retard nip by a nip guide 208. As a result of the coefficient of friction being greater between the retard pad 202 and a sheet and the feed roll and a sheet, should a double sheet enter the retard nip, the lower sheet is held back by the frictional force of the retard pad while the upper sheet is singularly fed through the nip and into the paper path. The lead edge of sheet 250 then contacts the flexible resilient strip 206 while still within the retard nip. This flexible strip 206 causes a corrugation of the sheet parallel to the direction of travel thereby increasing the beam strength of the sheet 250. The strip tends to raise the portion of the sheet 250 engaged as the remaining portions of the sheet are urged through the retard nip by the roller 104. This corrugation of the sheet helps to minimize the sheet flutter and vibration while it is within the retard nip and thereby decreases the audible noise created by the vibrating sheet 250. As discussed previously, the sheet is then forwarded through the baffle 106 (Fig. 1) to the take-away rolls 108 (Fig. 1). Turning now to Fig. 4, a second embodiment of the retard feeder with the noise suppression device of the present invention is illustrated. The feeder 200 consists again of a feed roll 104, a retard pad 202 and has a ramped section 210 built into the retard pad downstream of the retard nip. Again, the top sheet 250 is fed as in the previous instance and is separated to a single sheet by the retard nip. The ramped section 210 acts to corrugate the sheet in the same manner as the flexible strip 206 of the previous embodiment. This corrugation again increases the sheet beam strength and reduces the audible noise created by the sheet feeder. In recapitulation, a sheet feeding system which feeds sheets from a stack of sheets to a sheet transport path has been described. Specifically, the device includes a sheet feeding friction device for engaging and moving sheets in a direction toward the path, a retard pad positioned adjacent said sheet feeding device to form a retard nip to permit selective feeding of individual sheets through the retard nip to the path, and a raised portion in the path for corrugating the sheet as portions of the sheet are engaged in the retard nip. This corrugation increases the beam strength of the sheet and reduces the sheet flutter and vibration which results in a reduction of the audible noise associated therewith.

Claims: An apparatus for feeding individual sheets while reducing the noise associated therewith, including feeding means (104, 202) for advancing and separating individual sheets from a stack in a first direction; the feeding means (104, 202) including a frictional retard pad (202); a raised member (206, 210) for corrugating the individual sheets in a direction parallel to the sheet direction, located downstream of said retard pad (202) in the first direction, said raised member being adapted to reduce sheet flutter and the noise associated therewith, characterised in that said raised member (206, 210) is integral to, or is secured at one end to, said retard pad (202) and extends away from said retard pad (202) in the direction of sheet travel, said raised member further having a low coefficient of friction. An apparatus as claimed in claim 1, wherein said raised member comprises a ramped section (210) integral to said retard pad An apparatus as claimed in claim 1, wherein said raised member comprises a flexible strip (206) secured at one end to said retard pad. An electrophotographic printing machine of the type in which individual sheets are fed from a stack by a feeder having a device to reduce the noise associated therewith, the device comprising an apparatus as claimed in any one of claims 1 to 3. A method for reducing noise generated by feeding sheets by a retard pad feeding apparatus, said method comprising the steps of: urging at least one sheet in a sheet feeding direction to a retard nip; transporting a sheet through the nip in the sheet feeding direction; damping the vibrations induced in the transported sheet while in the nip so that audible noise generated by said transporting step is inhibited, characterised in that the step of damping includes corrugating the sheet during the transporting step by transporting the sheet over a raised member (206, 210) integral to, or secured at one end to, the retard pad (202) and extending away from said retard pad (202) in the direction of sheet travel, the raised member further having a low coefficient of friction.

Inventors: PALMATIER RICHARD, PALMATIER, RICHARD
Applicants: XEROX CORP, XEROX CORPORATION
Application year: 1994
Main classification: B65H3
IPC codes: G03G15, B65H3